Introduction

I get to attend great medical conferences on health and wellness and have noticed that there is mushrooming interest in mushrooms (if you can excuse the pun).

In particular, I notice that mushrooms are really popular in the over 50 year old speakers/experts at these conferences.

Several high profile medical herbalists mentioned during their presentations that they personally either take mushrooms daily or apply mushroom based products to their ageing faces.

Given the calibre of the speakers (and possibly the fact that a new season of NCIS had been released), I decided to take things at face value and buy myself some mushroom supplements – without doing my own research.

Until I saw the price tag. Wow. Some of these mushroom supplements are crazily expensive.

Sorry, Agent Gibbs. I need to leave you (and your shameless promotion of Starbucks) and do some research. We have previously looked at Rishi and Lion’s Mane Mushrooms. This time we look at maitake mushrooms.

What Are Maitake Mushrooms?

Wild mushrooms have been used as a food source by humans and animals for centuries. Currently over 5 million metric tons of mushrooms are cultivated annually. Over 700 species of mushroom have been reported to have medicinal properties.

Over 126 medicinal functions have been attributed to the medicinal mushroom family including anti-tumor, immunomodulating, antioxidant, radical scavenging, cardiovascular, anti-hypercholesterolemia, antiviral, antibacterial, anti-parasitic, antifungal, detoxification, hepatoprotective, and anti-diabetic effects (1).

There is even an International Journal on Medicinal Mushrooms (2). The global sales of medicinal mushroom supplements are 6 billion USD annually (3). Maitake mushrooms are one of those medicinal mushrooms.

Maitake mushroom (Grifola frondosa) is a large basidiomycete polypore mushroom which is indigenous to Japan.

The word Grifola refers to the Greek bird, the griffin, which has the head of an eagle and the body of a lion.

The word frondosa means leaflike.

The word ‘maitake’ comes from ‘mai’ which means dance and ‘take’ which means mushroom. There is controversy in the literature as to the origins of the dancing reference.

Some think that as the fruiting bodies of the mushroom can overlap that they can appear to dance, while others point out that the value of these mushrooms equalled its weight in silver and mushroom seekers would dance for joy if they found them (4).

Maitake mushrooms are also referred to as ‘hen of the woods’ as they apparently look like the feathers of a hen.

Other names for the maitake are kumotake (Japan) gray flower tree (China) and polypore en touffe in France.

The fruiting body of the mushroom is dark brown and fleshy and changes to a lighter grey color with age. They are usually found at or near the stumps of dead or dying hardwood trees and grow particularly well in Japan and the northeastern USA.

Fruiting can continue on dead trees or stumps and it spreads through submerged rotting roots by underground mycelium.

Medicinal use of maitake mushrooms date back to ancient Chinese and Japanese medical texts where they were used to boost qi.

A review published just this year helped us understand the key constituents in maitake mushrooms (5).

The main bioactives in maitake are are 1-3 and 1-6 beta-D-glucans.

It is also a rich source of trehalose which is used as a food preservative sweetener and vaccine stabiliser.

The main macronutrient breakdown of maitake is:

  • Water 17.4%
  • Fat 20.3%
  • Food fibre 0.1%
  • Carbohydrate 46%.

The key micronutrient content is as follows:

  • Vitamins and minerals (mg/100 gm)
  • Vitamin B1 3.8 mg
  • Vitamin B2 11 mg
  • Choline 850 mg
  • Niacin 73.5 mg
  • Innositol 347
  • Calcium 820
  • Phosphorus 4550
  • Iron 86
  • Magnesium 930
  • Potassium 3390

Prior to the 1980s maitake mushrooms could not be grown but nowadays commercially cultivated maitake mushrooms are available

There are 104 maitake based products for sale on Amazon with a standard capsule costing on average $0.12. As mentioned, some mushroom supplements are super expensive.

Is There Any Research?

There are 388 articles and 7 clinical trials published on maitake mushrooms. To put this into context, there are almost 18,000 publications on mushrooms which include 120 clinical trials.

Do Maitake Mushrooms Lower Cholesterol Levels?

There are no human clinical trials studying maitake and cholesterol in humans. We do have data from animal models.

A 1996 study showed that maitake mushrooms could prevent accumulation of lipids in the liver and blood using a Sprague Dawley rat model (6). While this sounds promising the authors caution that we need to establish the mechanism of action of the mushrooms before we can transfer this to humans.

A 2013 study in mice showed that maitake mushrooms can lower lipids in cholesterol fed mice (7).

Bottom Line

We cannot comment on the lipid lowering potential of maitake mushrooms in the absence of human clinical trial data.

Do Maitake Mushrooms Promote Fertility?

pregnant ladyJapanese investigators looked at maitake mushrooms in an open trial in 80 patients with polycystic ovarian syndrome at three clinics in Japan (8). Patients were allocated to three arms based on their clinical status:

  • 72  patients were randomly assigned to receive maitake or the standard treatment of clomiphene
  • 18 of these patients who did not respond to maitake or clomiphene were treated with a combination therapy of both agents for up to 16 weeks.
  • 8 patients with documented history of failure to standard clomiphene therapy received combination therapy.

Ovulation rates were lower in the maitake arm (76.9%) as compared to the clomiphene arm (93.5%) but this still has to be seen as an impressive ovulation rate in the maitake arm. It would have been really nice to have a no treatment (control) arm to see the benefit of maitake over no treatment at all.

A total of 13 patients out of 15 patients who had combination therapy were shown to ovulate on combination therapy. The study authors concluded that maitake mushrooms may be helpful either alone or in combination with maitake mushrooms.

Bottom Line

Maitake mushrooms are not a panacea for fertility issues. They may be helpful alone or in combination in some women with polycystic ovarian disease.

Does Maitake Mushroom Boost Immune Function?

A 2015 publication reported the findings of a study looking at the effect of maitake mushrooms in 21 patients with myelodysplastic syndrome (MDS) (9).

MDS is a bone marrow disorder that can result in low levels of blood cells and/or dysfunctional blood cell lines. Dysfunctional white blood cells put affected patients at risk of infections including life threatening infectious diseases.

In this study, statistically significant improvements in the functioning of neutrophil and monocytes white cell lines was noted. The assessment of the white cell subtype functioning was done ex vivo (meaning that the cells were taken out of the patient and tested in a laboratory).

This does not definitely prove that maitake would improve white cell function in vivo (in real humans) but it is a signal that this might be a useful strategy and is worth studying some more.

Researchers in Kentucky studied maitake mushrooms in 8 week old female mice and found significant improvements in natural killer cell activity, white cell function and secretion of key messengers in the inflammatory cascade (10).

Bottom Line

There are no human clinical trials to inform our thinking on the connection between maitake mushrooms and immunity. As we will see later, there are enough compelling pre-clinical data to raise concerns about the safety of these products in people with immune dysfunction or who are taking immunomodulators but not enough pre-clinical data to convince us to prescribe these agents in the absence of clinical data. Primum non nocere (11). Above all else, do no harm.

Does Maitake Mushroom Balance Blood Sugar?

Diabetic and control rats were given an experimental diets for 100 days which consisted of either 20% maitake or a control diet (12). The study found that the glucose levels in the diabetic rats who received maitake were significantly lower than those in the diabetic arm who took the control diet.

The animals were sacrificed and increased insulin antibody stains were noted in the diabetic maitake arm of the study which suggests more insulin activity in the maitake arm of the study.

Similar results were found in an earlier 1994 study which was carried out by a private company with interests in maitake (13). This study showed decreases in glucose, lipids and increases in insulin in maitake fed diabetic mice.

There are almost 30 similar studies in the literature. However, they all involve our furry friends and not humans.

Bottom Line

There is no clinical research in humans to help us understand if maitake can help with blood sugar control.

Do Maitake Mushrooms Reduce Blood Pressure?

A 2010 study from the US found that maitake mushroom fractions could lessen age-related hypertension in rats (14).

An even older study (1989) showed that 8 weeks of maitake mushroom supplements reduced blood pressure in 10 week old hypertensive rats but did not reduce cholesterol (15).

There are three similar studies looking at maitake for BP in rodents but there are no human clinical studies.

Bottom Line

There are no human clinical trials to guide us on whether Maitake reduces blood pressure.

Does Maitake Mushroom Kill Cancer Cells?

A  2017 study from China showed that maitake mushroom (especially when combined with vitamin C) has significant antitumor effects in neuorglioma cells (brain tumour cells) in a laboratory model (16).

A veterinary study in 15 dogs with lymphoma looked at maitake mushroom extract over 12 weeks. There was no control arm in this study. Unfortunately 13 of the 15 dogs developed disease progression before the end of the fourth week of the study which basically was interpreted as failure of the maitake as a chemotherapy agent for lymphoma (in dogs at least) (17).

As mentioned above, researchers at Memorial Sloan Kettering Cancer Center looked at 21 patients with a bone marrow disorder known as myelodysplastic syndrome (8).

It is classified as a form of bone marrow cancer where blood cell lines can be reduced in number and/or defective. All patients recieved oral maitake extract at 3 mg/kg twice daily for 12 weeks.

A total of 21 patients finished the study. The maitake supplement was well tolerated and resulted in significant improvement in white cell function.

Chinese investigators looked at the effect of a Chinese herb medicine Zhuling (Grifola umbellata pilat) on recurrence of bladder cancer (18).

This was compared to other preventative agents including  BCG, mitomycin C, thiotepa, afterloading brachytherapy and a control group. They found that bladder cancer recurrence occurred in 34.9% of the Grifola arm which was the lowest rate of recurrence in the study.

Another study from Memorial Sloan Kettering looked at maitake in 34 postmenopausal breast cancer patients (19). The aim of the study was to evaluate the effects of maitake on immune function. As mentioned in other articles, the immune system is really complex and as yet imperfectly understood.

This study found that the maitake mushroom supplement significantly increased certain parts of the immune system and decreased other parts of the immune system. The bottom line of this study was that maitake mushroom had an immunodulatory effect.

I agree that this is not exactly the best study to reference here but it is one of the three human clinical studies looking at maitake in cancer and as such was included.

A comprehensive review of the literature on reishi and maitake mushrooms in breast cancer published this year postulated that maitake mushrooms could exert an anti cancer effect by:

  • beta glucans modulating the immune system and/or
  • vitamins, minerals and amino acids boosting general health (5).

They concluded that most of the research was recent and based on cell lines or animal models and that well designed clinical trials were needed.

Bottom Line

The entire human clinical literature on maitake in cancer consist of just three studies. Two of the three studies looked at immune function and not cancer per se. The third study looked at bladder cancer recurrence and dates back to 1999 with no follow up which is not exactly encouraging. All in all, there is no reliable clinical information on maitake in cancer.

Is Maitake Mushroom Safe?

Care is generally recommended in people on blood thinning agents as maitake mushrooms can increase the effects of these agents. For the same reason it is not recommended that maitake mushrooms be eaten in the days immediately prior to a surgical procedure.

Care is also recommended in people taking medication for diabetes as maitake may contribute to lowering blood glucose.

A consistent message from the 2018 conferences on health and wellness was that mushrooms are best avoided in people with immune mediated disorders or who are taking immunosuppressant or biologic agents.

Reason being that there is an overall signal that mushrooms affect the immune system and that this is improperly understood at this time. Again, primum non nocere – above all else, do no harm.

Conclusion

A 2009 systematic review of the scientific evidence on maitake from researchers in Massachusetts General Hospital searched electronic databases and extended the search to journals not indexed in databases and bibliographies from secondary references (20).

They pretty much left no stone unturned. They concluded that there was ‘a lack of systematic studies on either the safety or effectiveness of maitake mushrooms’.

It would be difficult to recommend spending hard earned cash (yours or mine) on maitake.